Synthesis of phthalideisoquinolines by direct coupling of phthalide anions with 3,4-dihydroisoquinolinium salts

Abstract

The condensation of phthalide anions, derived from phthalide itself and from its 6,7- and 5,6-dimethoxy derivatives, with 6,7-dimethoxy-2-methyl-3,4-dihydroisoquinoline is described. The reaction products obtained in ca. 40% yield are easily separable mixtures of substituted (±)-erythro and (±)-threo-phthalidetetrahydroisoquinolines. The reaction is potentially useful for synthesis of naturally occurring akaloids of this family.